I received a completely blank newspaper in the mail...SUPER SECRET! BAD? PORN?

No. It was from Freedom From Religion in Politics. At least that's what I recall it said since I never got a chance to read it before someone else accidentally threw it out (damn it). I had put it in a pile of junk mail but since I am curious by nature I opened it on the way to recycle and it turned out to be from an organization I recently donated money to after seeing the zillionth ad on TV with Ron Reagan Jr. I have been a lifelong Atheist (my whole family is despite going to CCD until I was 7 or 8 and was finally told I had a choice and could choose what I wanted to do...I chose to sleep late on Sat AM, thank you very much). Anyway, I never donated to any religion since I don't believe it is realistic or has positive aspects in any way for me personally. I thought I should donate now since I recently began donating in small amounts to democrat organizations, publications, legit print media, etc. Back to my point...why was this publication sent to me in such a format? It's an Atheist group and I donated $25 specifying it to be used in advertising (like Ron Reagan Jr) to spread the word to keep religion out of politics (separation of church and state, AKA the constitution). It's not an evil organization so why was it's origin concealed? If I receiver something from the KKK it probably would arrive in my mail with bold, neon print all over it and that would be OK. So why does an innocent and peaceful organization have to conceal itself from the public mail? Please explain this hypocritical practice to me because it makes no sense to me whatsoever.)